High-resolution X-ray photoelectron spectroscopy in studies of self-assembled organic monolayers

This article reviews recent progress in the characterization of self-assembled monolayers (SAMs) with a chalcogen headgroup by synchrotron-based high-resolution X-ray photoelectron spectroscopy (HRXPS). We present reference data for archetypical, most frequently used SAM systems and discuss specific effects and SAM properties which can only be observed at high energy resolution. We show that not only the emissions related to a SAM but also those related to the substrate can provide important information on the system under study. We demonstrate that the standard chemical shift framework is not always sufficient to explain photoemission from SAMs, but, in some selected cases, electrostatic effects should be taken into account as well. General aspects of XPS and HRXPS experiments on SAMs are discussed, including X-ray induced damage and proper calibration procedures.